This invention relates to arresting systems usable to arrest travel of a vehicle and, more particularly, to such systems capable of arresting the travel of an aircraft, such as a tactical fighter aircraft, under emergency or other conditions.
Aircraft arresting systems have been in use for many years. Prior such systems of the present general type typically include a barrier net or tail-hook cable stretched transverse to a runway at a point along or at an end of the runway. The net or cable is attached at each end to energy absorber units positioned on opposite sides of the runway. In one form, each energy absorber unit utilizes a flexible tape wound on a reel whose rotation is controllably braked by a braking mechanism employing friction. In prior configurations, each energy absorber unit typically had a height of the order of five to six feet, so that the two units were required to be set back a considerable distance on respective sides of the runway (e.g., set back about 200 to 300 feet) or, if located closer to the edge of the runway, were required to be installed below surface grade in concrete vaults of significant depth to accommodate the height of the absorber units.
With an arrangement as described, arrestment occurs when an aircraft, which may be traveling at high speed, engages the barrier net or tail-hook cable positioned across a runway. As the aircraft tail hook engages the cable, for example, displacement of the cable in the direction of aircraft travel begins to pull the arrestment tape out of the absorber units on opposite sides of the runway. As each tape is unwound from a tape spool, it produces rotation of the tape spool about an axis of rotation aligned horizontally. Tape spool rotation is braked by a frictional or other brake unit positioned adjacent to the tape spool. In prior systems, a small gasoline engine or other arrangement may be incorporated for use in rewinding the tape after its deployment for arrestment of an aircraft.
The degree of braking may be controlled by application of hydraulic pressure for brake activation. The profile of brake application with passage of time as the aircraft first engages the system and is then brought to a stop may be computer controlled. Such control enables efficient, non-destructive arrestment of aircraft travel, without exhausting the length of arrestment tape available on the tape reel in each absorber unit. U.S. Pat. No. 5,042,750, entitled Aircraft Arresting System and having a common assignee with the present invention, describes a system utilizing computer controlled braking for effective aircraft arrestment.
Objects of the present invention are to provide new and improved arresting systems which may have one or more of the following characteristics and capabilities:
low profile, with system height of the order of one foot;
compliance with airport obstruction regulations to permit above-ground installation at the edge of a runway;
brake-in-spool configuration with a brake assembly positioned within the hub of each tape spool;
arresting tape maintained pre-tensioned on the tape spool;
tape spools configured for one-time use and replacement after an aircraft arrestment;
no rewind engine or other mechanism for rewinding of arresting tape after deployment;
system configured to enhance tape spool removal and replacement;
system enclosure configured to withstand roll-over by aircraft wheels; and
system enclosure using aircraft landing mats for upper cover and lower structure.
In accordance with the invention, an arresting system, for aircraft arrestment, includes a support assembly, brake assemblies, tape spools and a coupling device. A first brake assembly is supported by the support assembly and includes a stationary portion, a first rotatable portion configured to support a first tape spool rotatable about a nominally vertical axis, and a braking mechanism to brake rotation of the first rotatable portion. A second brake assembly is supported by the support assembly in horizontally spaced relation to the first brake assembly. The second brake assembly may be of the same configuration as the first brake assembly. First and second tape spools are removably supported by the rotatable portions of the respective first and second brake assemblies. Each tape spool includes a spool hub configured to encircle and rotate with the respective rotatable portion and an arresting tape wound on the spool hub. The tape spools and rotatable brake assembly portions may be configured so that the braking mechanism of a brake assembly is within the spool hub when a tape spool is supported by a rotatable brake assembly portion. A coupling device is attached to one end of the arresting tape of each of the first and second tape spools to enable attachment to an aircraft engagement unit (e.g., a tail-hook cable) positionable transverse to a runway.
Also in accordance with the invention, a tape spool, usable in an arresting system having a brake assembly including a rotatable portion configured to support the tape spool, includes the following. A spool hub is configured to encircle the rotatable portion of the brake assembly and to be removably supported by the rotatable portion for rotation therewith. A length of arresting tape is wound on the spool hub and may be maintained in a pre-tensioned condition. The spool hub may include internal keying features configured to cooperate with external keying features of a rotatable brake assembly portion to enable slidable installation of a tape spool in fixed rotational relation to the rotatable portion.
For a better understanding of the invention, together with other and further objects, reference is made to the accompanying drawings and the scope of the invention will be pointed out in the accompanying claims.